The inventor is aware of the following prior patents relating to the hammering tool of the present invention:
A. U.S. Pat. No. 2,809,684, which discloses a plate spring, one end of which is connected to the hammering block, and the other end of which is connected to a grip handle. However, the single plate spring is a rectangular flat piece, so under the shocks resulting from the impacts during normal use of the tool, the hammering block will tend to slide back towards the grip handle. Furthermore, after being used for a certain time, this single plate spring will, due to its insufficient stiffness, tend to become deformed, thus making its further use relatively impractical. PA1 B. U.S. Pat. No. 1,177,472, in which the gripping handle and an axe blade are flexibly joined. However, the flexible connection plates are similar to that disclosed in the '684 patent noted above, hence its inadequate rigidity may become troublesome. PA1 C. U.S. Pat. No. 4,331,193, in which a plate spring is implanted in the gripping handle of the hammering tool, and in which the end of the spring is joined to a hammering block. This design may provide the hammering tool with some flexibility; however, its structure is more complicated and its utilization is more difficult and also uneconomic.
Other prior art, of which I am aware, is as follows: U.S. Pat. Nos. 587,154; 967,703; 1,194,170; 2,467,284; and 3,393,720.